Hitherto, the issue of the war in Afghanistan has seemed straightforward. In contrast to Iraq, Afghanistan has been the “good war” – a war of necessity, fought to make sure that a repeat of the 9/11 attacks, directed from Afghanistan by an al-Qa’ida sheltered by the Taliban, would never occur again.

Underlining this reinvigorated commitment, Mr Obama authorised an increase in US strength in Afghanistan to 68,000 by the end of the year, and named General McChrystal, previously in charge of US special forces, as his new commander on the ground. But the latter’s recommendation of a boost of 30,000 to 40,000 confronts this president with a dilemma akin to that facing his predecessor over Iraq three years ago: to surge or not to surge? And views within the administration differ sharply.

Essentially the choice, in strategic jargon, is between counter-terrorism and counter-insurgency. The latter, implying a broad war against the Taliban to prevent it returning to power, seems to be what General McChrystal has in mind, and has long been backed by Mrs Clinton. Only this week, she had scathing words for those who argued that al-Qa’ida was no longer a factor in Afghanistan. “If Afghanistan is taken over again by the Taliban, I can’t tell you how fast al-Qa’ida would be back.”

The Vice-President, on the other hand, wants a narrower focus on al-Qa’ida itself, both in Afghanistan and Pakistan, where security forces have scored some important recent successes against the terrorist organisation and its Taliban allies. Under this approach, the US would require fewer forces in the field.

Instead of trying to protect the general population from the Taliban and operating a “hearts and minds” policy to win over civilian support, it would concentrate on targeted strikes on al-Qa’ida operatives, relying on umnanned drones, missile attacks and the special forces where General McChrystal is an expert. Simultaneously the training of Afghan government forces would be speeded up.

A third faction advocates a compromise, either scaling back the requested troop increase, or even starting to reverse it, while at the same time ensuring that the country does not collapse into chaos.